Proper usage of T21 4p

[Katboet]

What's the proper usage of the Tier 21 4-piece? Every time Charged Up is off cd, should I Arcane Barrage and immediately charged up? Should I wait until Arcane Power is off CD? Working the 4 bonus into my rotation has been confusing me some!

[roldy]

snip

Charged up has a 40s CD arcane power has a 90s CD. So you use it on pull, once when it comes of CD and the third one you have to delay slightly to use it with AP again.